This invention relates to a method for producing steel by the open-hearth process, and more particularly to an improved method for operating an open-hearth furnace by introducing oxygen and fuel into the bath, beneath the surface, in a specified orientation and for a determinable period of time. A new sequence of stack damper operation enhances the operation of the furnace.
The utilization of oxygen to assist in refining of steel in an open-hearth furnace has long been known and is described in U.S. Pat. Nos. 2,878,115; 3,115,405; and 3,859,078, among others. Heretofore however the tap-to-tap times still remain approximately 4 hours for 200 ton heats as opposed to about 7 hours for a furnace operated without oxygen.
In the top blown oxygen injection arrangements in the prior art, oxygen lances or tuyeres protruding through the roof burn downward into the metal and damage the bottom lining. Tuyeres which are horizontal and perpendicular to the side walls of the furnace lining as shown in U.S. Pat. No. 3,859,078 create a bottom build-up in the non-active areas, which results in incomplete reaction of the bath components, and leaves molten metal pools in the furnace upon tapping.
I have found that by injecting oxygen into the bath of an open-hearth in the proper location and at the proper angle, I am able to obtain tap-to-tap times on the order of an hour and 45 minutes for 200 ton furnaces.